Battery and separator therefor



F. T. BAIRD.

BATTERY AND SEPARATOR THEREFOR.

APPLICATION FILED AUG-3U. I920.

Reissued Mar. 22, 1921.

UNITED STATES PATENT OFFICE;

FRANK T. mini), or BLUE ISLAND, ILLINOIS.

BATTERY AND SEPARATOR "IIIEREFOR.

Specification of Reissued Lettersratent. Rei u Dial. 22 1921 OriginalNo. 1,279,074, dated September 17, 1918, Serial No. 202,7 2 0, fi1edNovember 19, 1917. Application for reissue filed August 30, 1920. SerialNo. 407,048.

gives low internal resistance to the battery.

It is desirable that it shall have high absorptive properties, thusenabling it, when used in adry battery, to retain in itself a sufficientquantity of the electrolyte to enable the battery to functionefficiently and to prevent the liquid from running out in case the cellis overturnedor punctured. It is desirable that it shall be porous sothat it may be readily washed. It is desirable that it shall be softenough not to injure the battery plates nortend to remove the activematerial from them. It is desirable also that it shall be simple tomanufacture, inexpensive, and made from material easy to ob tain. I havediscovered that a separator combining the mentioned characteristics maybe obtained by making it of tripoli as will be explained.

While the separator and battery in which it is used may assume variousforms, I have illustrated a suitable one in the accompanyshown in thedrawings: The outer plates 1, 1

ing drawings, in which: 7 igure 1 is a perspective view of the positiveand negativeplates of a battery showing my separators in position.

Fig. 2 is a perspective view of the form of separator used in thisparticular type of battery, and

Fi 3 is a sectional view taken on the line 3, 3, Fig. 1.

1 In the drawings, similar parts are in-.

(heated by similar reference characters in the several views.

To describe the particular style' of battery are negative and the innerones 2 positive.

These consist usually of leadhaving suitable active material upon theirsurfaces. The

negative plates are connected by a lug 3 and the positive plates arehere shown to be formed in three layers, connected by a lug 4. Theseparatorso are interposed between the positive and negative platesand,by preference, are substantially equal to them in s ze. They arecomposed of a material technically known as tripoli which is defined as.a siliceous deposit almost wholly-of the shells of diatomsand occurringin friable masses or earthy form. I have discovered thatthis material iscapable of absorbing sufiicient electrolyte topermit portable batteriesto discharge effectively for as long a period as can be expected frommost commercial dry cells in which the electrolytic liquid is present insuch quantitiesthat it will run out in case an o enin is made in theshell or jacket. In o-t l ier n ords, a battery using my separators doesnot contain electrolyte which is free in the sense of being able to bedrained off in case of puncture. The electrolyte is present in adequatequantity but isheld absorbed by thesepai'ators.

My separators are usually formed by sawmg them from masses of tripoli inthe native state. No treatment of any kind is ordinarily required. Thetripoli itself is found in large qualities in Missouri and other Statesof the United States in a very pure state and exhibiting thecharacteristics which are so valuable and which render my battery soefiicient.

It is well known that in the ordinary dry battery, as soon as theelectrolyte liquid has been drained off, the battery loses itsefiiciency, if not most of its ability to function at all. In a batteryemploying my separator on the contrary, the cell will continue tofunction as long as maybe expected from any so-called dry cell. I havediscovered,

furthermore, that tripoli has such porosity as to present very lowresistance, the result being that a battery employing this material as aseparator has low internal resistance. I have also discovered that afterthe battery has been apparently discharged (so far as ordinary practicalconditions are concerned) and the voltage has dropped to about 1.5volts, a considerable added period of service may be obtained by pouringfresh water upon the separators; for example, when the battery hasdischarged to about 1.5 volts, b

removing the se I arators and pouring fresli (preferably distilled)water upon them and reassembling the battery, an additional service ofone and one-half hours may be ohtained from asma ll. portable batterywithout recharge. v i I p y The effect of the ordinary electrolyte uponthe tripoli separator seems-to be to soften thesurface. Such aseparator, therefore, is

easy upon the battery platesin the sense. that it does not abrade theplates or tend to rea move theaotive material. from their faces. Theplates themselves, therefore lastmuch longer withxm'y separatorsthanwith others,

having harder or more abrasive surfaces) Batteries constructed 111 themanner de- 1 scribedand-employing separators of tripol i maybe rechargedby connecting them in a charging, circuit in the same manner as isemployed "in the-recharging of Wet batteriesJ I have foundthat'theconstitu- H encyv ofmtripoli is such that it distributes theelectrolyteover the entire area of the separatorf thus making forefliciency in thebattery. As a "result of my" inven tionor; discovery; Iam able to produce a battery: and separator easily and cheaply frommaterials which occur abundantly close at handin a state of nature. I amalso ableto procure abattery which will not leak or drip in caseltheshellor'oasing is punctured or inverted, and willa'recuperate for anadditionaliperiod; of "service by merely Washing the separators or?permitting fresh water to ;flow "upon them. The 'interna1 resistance-isheld at a low point anddistribm tion of the electrolyte throughout thearea of theseparatoris uniform, owing.,i I believe, to the capillarycharacteristics of the material. r a I Having thus described myinvention what I claims-as newand desire to seoureby Let- 'ters Patent,is i a a r 1. VA batteryseparator 'f ormedof tripoli. for storagebatteries,

2.-A separator formed by sawingtripoli .in" its native state into slabsor sheets. p i recharge dry 'battery whose electro lyte is" absorbed bythe separators, substantially-completely, and whoseuplates have activematerial whereby the battery may be recharged.

4 A secondary-battery having separator plates of sufficient absorptivecapacityto reand discharging, a v p a Ap sto'rage batteryhavingpositiveand negative "platesand separators of porousand absorptive characterhaving an absorptive capacity suflicient to enable them to absorbeno'ugh electrol yte to render the battery optain all the electrolyterequired for charging upon their surfaces whereby the battery may berecharged'.- 5 v 1 r a In" witness whereof; I haye'hereunto subscribedmy name in the presenceof two wit nesses.

Witnesses a DWIGHT B; CHEE'VER,

AQTNAROVSENTHALL \erative, :the' plates having activemateria'l

